Recently, applicants isolated an hLH beta core fragment (hLHβcf) from human pituitaries. This molecule is homologous to the hCG beta core fragment (hCGβcf), which may be a marker of normal pregnancy, Down syndrome, and certain cancers. Applicants now report antibodies to the hLHβcf, four of which have been applied in sensitive immunoradiometric assays for urinary measurements. One of the antibodies recognizes an epitope on the hLHβcf, which is not present on the hCGβcf, hLH, or hLHβ. This specific hLHβcf antibody acts cooperatively with other newly-developed antibodies reported here to produce an assay with a sensitivity of 1 fmol/ml of hLHβcf. The specificity of these new IRMA systems will make it possible to measure the hLHβcf in urine in the presence of hLH, hLH beta, or the hCGβcf. Although the hLHβcf used to develop specific antibodies was purified from pituitaries, the assays developed recognize this metabolite in urine. Measurements of heterodimeric hLH as compared to hLHβcf in the urine of cycling women indicated that the concentration of hLHβcf rose as high as 6-7 times the concentration of hLH starting a day after the midcycle surge. The new measuring systems allow the precise quantitation of this hLH metabolite in urine.
Understanding of the metabolites of the gonadotropins excreted into urine may help to distinguish between healthy and abnormal physiological states. For example, the hCG β core fragment (hCGβcf) is present at high levels in the urine of normal pregnant women (Kato et al., 1988) but, also, occurs abnormally in the urine of nonpregnant patients with a variety of malignancies (O'Connor et al., 1988, Cole et al., 1988a,1988b,1990). Applicants and others have observed a beta core fragment of hLH (hLHβcf) in the urine of normally cycling women shortly after the hLH midcycle surge (Neven et al., 1993) and in the urine of postmenopausal women (Iles et al., 1992). Both the hCG and hLH fragments have analogous structures (Birken et al., 1993) but, it has not been possible to measure one of the fragments in the presence of the other. For example, the utility of the hCGβcf molecule as a marker of malignancies in postmenopausal women has been compromised by the cross-reactions of antibodies elicited to the hCGβcf with a molecule of similar structure and size (presumably the homologous fragment of hLH) excreted by normal postmenopausal women in their urine. Consequently, the high threshold measurement compromised the ability of hCGβcf to serve as a cancer marker in this important patient population. Applicants had earlier suggested the hypothesis that, if it were possible to distinguish an hLHβcf from an hCGβcf, a preponderance of the former might be indicative of the normal state while a major mole fraction of the hCG fragment may be associated with malignancy (Birken et al., 1993). Immunological analysis of the hLHβcf in normal cycling women, as compared with infertile patients, may identify a metabolic marker associated with an abnormal state (i.e.an ovulatory cycles, polycystic ovarian disease). For these reasons, applicants have developed a series of antibodies to the hLHβcf, which was isolated from a pituitary extract but, as reported here, can also be used to measure such a molecule in urine.
Although antibodies to the hCGβcf could be used to extract the hLH-associated core materials from normal postmenopausal women, it was difficult to generate sufficient material to even characterize the structure of the molecule present in urine. Instead, applicants were able to successfully isolate an hLHβcf from human pituitary extracts (Birken et al., 1993). Using this material, applicants now report the development and characterization of immunometric measurement systems to quantitate the pituitary hLHb core fragment in urine. These assays will now make it possible to evaluate the metabolism of hLH in both pre and postmenopausal women and to possibly distinguish between normal and abnormal physiological states.